Chicago Police detectives investigate the scene where 13 people, including a 3-year-old child, were shot in a city park in Chicago. / Paul Beaty, AP

by William M. Welch and Doug Stanglin, USA TODAY

by William M. Welch and Doug Stanglin, USA TODAY

Chicago Mayor Rahm Emanuel called Tuesday for a three-year minimum prison sentence for illegally carrying a gun as authorities brought attempted-murder charges against four men in one of the latest gang-related shootings that have plagued parts of the city.

Police arrested and charged the four with attempted murder in the drive-by shooting at a city park that wounded 13 people, one of them a 3-year-old boy who was shot in the face.

"As we invest heavily in programs for youth, in new policing strategies and in building supports for those most likely to fall into gangs, we also need a three-year mandatory minimum bill for gun crimes,'' Emanuel said.

Police allege that Tabari Young, 22, opened fire with a military-grade weapon as he and a companion sped by Cornell Square Park on the city's southwest side. Young and three others -- Brad Jett, 22; Bryon Champ, 21; and Kewane Gatewood, 20 -- were charged with attempted murder and aggravated battery with a firearm. They were being held without bond.

Police said Champ was the second gunman in the car, Gatewood supplied the rifle and Jett served as a lookout.

Police Superintendent Garry McCarthy said Champ had been grazed in a shooting in the area earlier in the day and returned seeking revenge.

McCarthy said there was no specific target but that the men went to the park because it was rival gang territory.

"There's a superheated group of gunmen who were victims and offenders," he said. "This individual was a victim of gun violence and then became an offender."

Faced with rising gun violence, Emanuel has made curbing the shootings high priority and allowed the Police Department to spend millions of dollars in overtime to saturate high-crime areas with officers.

Through Sept. 15, police said, they've recorded 306 murders and 1,402 shooting incidents this year. Murders are down 20% and shootings are down 22% compared with the same period last year. Police said violent crime overall is down about 15%, according to new figures released Monday.

Young "was identified as the person who shot 3-year-old Deonta Howard and 12 other victims," according to the arrest report, the Chicago Tribune reported. Jett "was identified as one of the individuals who participated in the shooting," the report said.

The child is recovering from surgery after being shot near an ear.

Young's mother told the newspaper that his brother was shot and killed by Chicago police in 2008 and his father died last year after an illness.

McCarthy said Champ had been convicted of unlawful use of a weapon by a felon in 2012 and was sentenced to "boot camp" at the Cook County Department of Corrections instead of jail time.

"That is unacceptable," McCarthy said. "He received boot camp for that gun crime and was back out on the streets to be a part of this senseless shooting."

"To truly address violence for the long term, we need state and federal laws that keep illegal guns out of our communities and provide real punishment for the criminals who use them," McCarthy said.